The New York Times, August 23, recalls how the Wildenstein art dynasty added value to its product:
Upon Nathan’s death in 1934, Georges steered the family into an era of unprecedented prosperity by building an infrastructure around his artists’ markets. He organized exhibitions, edited an art journal and published definitive catalogs of works by artists in his inventory — Ingres, Fragonard, Chardin. (Daniel would later do the same with Monet, Manet and Gauguin.) The books were well respected and helped market their artists to museums.
This is a kind of Directional Investing.